#help-0

1 messages · Page 686 of 1

dawn wraith
#

Have you heard of;
sin(x)=cos(pi/2-x)?

hollow pelican
#

nope im quite new to further trigo

dawn wraith
#

It’s the relation of sine and cosine in a right triangle

#

If you were to try and use a calculator, you’d get the same values!

hollow pelican
#

ok, ill try it out

dawn wraith
#

Make sure that if for example you want the sin of pi/6

#

The cosine is 2pi/6

#

The identity could also be written as:
sin(pi/2-x)=cos(x)

hollow pelican
#

i got diff values tho

dawn wraith
#

How though

#

Oh sorry

#

It’s 2 pi

#

2pi/6

hollow pelican
#

ohh ok

#

i got sin positive and cos negative value

sage summit
#

shockingly, it was discovered that pi is not the same as pi/2

dawn wraith
#

XD

#

Yeah, I noticed that thank you

hollow pelican
#

yea

dawn wraith
#

So without further ado, @hollow pelican
You may replace the cos(pi/2-theta) with just sin(theta)!

#

From there, you’ve got a pretty simple trigonometric equation

hollow pelican
#

ok

dawn wraith
#

Only now the question is, is there another solution?

hollow pelican
#

I am not sure

dawn wraith
#

Hint, another identity

#

Got any ideas?

hollow pelican
#

hmm is it

dawn wraith
#

Nope, pay attention.

analog locust
#

what's P()?

dawn wraith
#

don’t barge in like that bud, haven’t you noticed that we’re talking here?

dawn wraith
hollow pelican
#

oh yes

#

I didnt heard of that

dawn wraith
#

Use that to find the second solution, and you’re set!

hollow pelican
#

okay

dawn wraith
#

That should be all, is there anything else?

hollow pelican
#

no, thanks btw

dawn wraith
#

Anytime.

pure hill
#

is this channel free??

dawn wraith
sage summit
#

it's true for any positive real number

analog locust
#

@dawn wraith oh sorry didn't noticed

dawn wraith
#

It’s fine.

hollow pelican
#

If i were to use this , is my working correct?

sage summit
#

yes

hollow pelican
#

ok thanks

native temple
#

if in conditional probability $$ P(B|A) = \frac{P(B) and P(A)}{P(B)} $$
and $$ P(B) = \frac{#Events}{Sample Space of A} $$
Since P(B) is being multiplied by P(A) and that is being divided out of P(A) doesn't that mean
$$ P(B|A) = P(B)?$$

ocean sealBOT
#

Nerdy_Coder
Compile Error! Click the errors reaction for more information.
(You may edit your message to recompile.)

glass lichen
#

it's P(B and A)

#

not P(B) and P(A)

native temple
#

sorry let me fix that(but still answer my question)

#

if in conditional probability $$ P(B|A) = \frac{P(B and A)}{P(B)} $$
and $$ P(B) = \frac{#Events}{Sample Space of A} $$
Since P(B) is being multiplied by P(A) and that is being divided out of P(A) doesn't that mean
$$ P(B|A) = P(B)?$$

glass lichen
#

If A and B are independent, then yes, conditional probability is just P(B)

ocean sealBOT
#

Nerdy_Coder
Compile Error! Click the errors reaction for more information.
(You may edit your message to recompile.)

native temple
#

oh

#

I see that's why it just doesn't say P(B)

#

because if they aren't mutaully exclusive....

glass lichen
#

Yeah..

native temple
#

then it's P(B)-P(A and B) right?

alpine sable
glass lichen
#

There's channels to test the bots

warped phoenix
#

seeing as to how you find the roots of a polynomial by setting it to 0, does that mean the roots are the x-intercepts?

glass lichen
#

yes..

warped phoenix
#

ok

warped phoenix
#

sorry my book is really shitty and didnt tell me that

glass lichen
#

roots, zeroes, x-intercepts are all equivalent

warped phoenix
#

they're teaching everything backwards and in the wrong order wtf
they show me a method in one lesson without explanation, then I have to spend an hour searching it up and learning it myself via youtube, only for them to explain it a couple lessons later

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they "Taught" me synthetic division before long division of polynomials and i had to take like an hour to figure out wtf synthetic division was

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and then they explain how to do it thoroughly like 4 lessons later

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@glass lichen so root is just another word for x-intercept? or does it server another purpose

glass lichen
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no

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they're just equivalent terms

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x-intercept is more general

native temple
#

$$text{Also use Ration Root(or Zero) Theorim as }\frac{p}{q} text{Helps you find the rational roots of ANY polynomial P = Leading Coefficent Q = Coefficent of Constant}$$

ocean sealBOT
#

Nerdy_Coder

glass lichen
#

....

#

OR, you can just put the stuff that needs to be tex'd in dollar signs

warped phoenix
#

you dont need to put {text}, just put the $ before and after any math

#

yeah

ocean sealBOT
#

Nerdy_Coder

$$\text{Also use Rational Root(or Zero) Theorim as }\frac{p}{q} \text{Helps you find the rational roots of ANY polynomial P = Leading Coefficent Q = Coefficent of Constant}$$
glass lichen
#

instead of fugly texs like that

#

also that's not what RRT says anyway

native temple
#

$$\text{Also use Rational Root(or Zero) Theorim as }\frac{p}{q} \text{Helps you find the rational roots of ANY polynomial P = Leading Coefficent Q = Coefficent of Constant}$$

ocean sealBOT
#

Nerdy_Coder

native temple
#

sigh

#

$$\text{Also use Rational Root(or Zero) Theorim as }\frac{p}{q}
\text{Helps you find the rational roots of ANY polynomial P = Leading Coefficent Q = Coefficent of Constant}$$

ocean sealBOT
#

Nerdy_Coder

native temple
#

there we go

glass lichen
#

can you stop spamming?

native temple
#

noooo

warped phoenix
#

Also use Rational Root (or Zero) Theorim as $\frac{p}{q}$ Helps you find the rational roots of ANY polynomial P = Leading Coefficent Q = Coefficent of Constant

ocean sealBOT
#

TheMane3

warped phoenix
#

there @native temple

gray isle
#

is not what rrt states

native temple
#

oh thanks

warped phoenix
#

ik i just fixed the text for him

#

whats rrt btw?

native temple
#

rational root therim

gray isle
#

the acronym for rational root theorem

warped phoenix
#

oh ok

glass lichen
#

A polynomial P(x) has a rational root when $x=\pm\frac{p}{q}$, were q is a factor of the constant term and p is a factor of the leading coefficient

ocean sealBOT
warped phoenix
#

wait so all a root is is just the x-intercept

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nothing more

glass lichen
#

yes

warped phoenix
#

"The roots of a polynomial are those values of the variable that cause the polynomial to evaluate to zero", wouldn't that just be what you put into f(x)? so in f(3), 3 is the root? the only value you can put in f(x) to make it equal to zero is f(0) though, right?

glass lichen
#

if f(3)=0, then yes

warped phoenix
#

ohhh

meager pulsar
#

Turn fractions into decimal numbers and sort results into exact decimals or periodic decimals with the calculations please

warped phoenix
#

f(3) would only ever equal zero if a, b, and c were 0 though :/

glass lichen
#

????

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tf are you on about

native temple
glass lichen
#

$f(x)=(x-3)(x-1)$, clearly $f(3)=0$

ocean sealBOT
warped phoenix
#

ohhh

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sorry

glass lichen
#

likewise, clearly f(0)=3 in that case (coincidence it ended up being 3 and 0 swapping)

native temple
warped phoenix
#

How do I know if x is approaching negative infinity and positive infinity?

native temple
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what?

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oh

warped phoenix
#

It says to evaluate the function using a large negative and large positive number

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but like...what's the threshold.

native temple
#

what function

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I think you have to check transformations

glass lichen
#

just check end behaviours..

warped phoenix
#

what is that

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this is the function

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they evaluate using -1000, and 1000, should I always use those numebrs?

glass lichen
#

yeah, end behaviour is dominated by the leading term

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so it's the same thing that happens to y=x^3

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which is an odd power and positive co-efficient, so x->inf means y-> inf x-> -inf means y->-inf

warped phoenix
#

im not sure i follow...

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wdym my leading term

glass lichen
#

the highest power term

warped phoenix
#

is (-1000)^3 and (1000)^3 the leading terms

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oh ok

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right

glass lichen
#

x^3 is the leading term..

warped phoenix
#

mhm

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so since x^3 is positive, seeing as to how x isnt negative, x --> + inf.

glass lichen
#

x^3 is positive if x is positive..

warped phoenix
#

right

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"Seeing as to how x isnt negative"

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that means it approaches pos. infinity right?

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but if x was negative, x --> -infinity ?

glass lichen
#

yes, for odd powers one end is +inf and the other is -inf

warped phoenix
#

because you have to evaluate the function with both a negative and positive number, got it

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when they say "large pos/neg. number", what's the threshold for that?

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anything above 1000?

glass lichen
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literally any big number

warped phoenix
#

100's pretty big..

glass lichen
#

then use 100

warped phoenix
#

ohhhhhhhhhhhhhhhhhhh

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😄

#

if x approaches negative or positive infinity, f(x) [so y basically] HAS to follow whatever one x is approaching right?

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if x --> + inf., y --> + inf.

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you said that before i think but i just wanted to make sure

glass lichen
#

no

#

end behaviour is reduced down to the same end behaviour as $y=\pm x^2$ and $y=\pm x$

ocean sealBOT
glass lichen
#

ie the leading term's degree's parity and leading co-efficient's sign

warped phoenix
#

whats parity

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the sign in front of x?

glass lichen
#

even and oddness of an integer

warped phoenix
#

ahh

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so how do i graph the function when x --> inf and x --> - inf

glass lichen
#

??

warped phoenix
#

like here

glass lichen
#

yeah, what about it?

warped phoenix
#

how do i know how far right and far left to go

glass lichen
#

the domain of a polynomial is R...

warped phoenix
#

whats a domain

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also R is the remainder right

glass lichen
#

no..

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R is the real numbers

warped phoenix
#

oh

glass lichen
#

domain is the input space

warped phoenix
#

wdym by input space

glass lichen
#

the space of values you can put into the function

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you should've learned domain as one of the 1st things..

warped phoenix
#

LOL thats the first time im hearing this word (theres the shitty alg 2 book doing its work again)

#

so its what you substitute for x?

finite spindle
#

in other words, it's all possible values you can substitute for x. in this case, all real numbers from -infinity to infinity

warped phoenix
#

ohh

glass lichen
#

$D_f=\mathbb{R}$ for any polynomial f

ocean sealBOT
finite spindle
#

some functions for example, like f(x) = 1/x , won't let you put in x=0

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so its domain would be all real numbers except 0.

warped phoenix
#

does that mean domain of a function = real numbers @glass lichen

glass lichen
#

no

warped phoenix
#

oh whats the f

glass lichen
#

"any polynomial f"

warped phoenix
#

ah so domain of a polynomial = real numbers

glass lichen
#

yes

warped phoenix
#

@finite spindle oh so the only two types of domains can be all real numbers, and all real numbers except 0?

glass lichen
#

No, clearly not

finite spindle
#

no, that was just one simple example

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for example the function f(x) = 1/(3-x) cannot have x=3

warped phoenix
#

oh ok, wait, so if x MAKES the denominator equal 0 then you exclude it

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oh ok

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right

finite spindle
#

for example yeah

warped phoenix
#

ahh

glass lichen
#

$f(x)=\ln(x)\implies D_f=(0,\infty )$

ocean sealBOT
warped phoenix
#

what's ln

glass lichen
#

natural log

warped phoenix
#

(what's that 😅 )

glass lichen
#

anyway, back to the regular question...?

dreamy mountain
#

Log but with e

warped phoenix
#

idk what a log is

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logarithm?

wary stream
glass lichen
#

it's not a polynomial

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since $\frac{1}{2}\notin \mathbb{Z}^+\cup{0}$

ocean sealBOT
warped phoenix
#

ok, so, if the domain = any real number, basically what you're saying is I can choose how far left or right the graph goes?

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after it hits the x int. ofc

glass lichen
#

yes, so long as the graph shows the intercepts / important features

warped phoenix
#

ohhhhhhhhhhhhhhhhhhh

#

awesome

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why are all of you better teachers than a multi-million dollar company's online schooling program....LOL

glass lichen
#

yeah, sqrt(x) isnt a monomial, since it's not a non-neg integer power dldh

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likewise with 1/x

ocean sealBOT
#

dldh06

glass lichen
#

$p(x)=\sum_{i=0}^n a_ix^i$ is polynomials of degree n

ocean sealBOT
wary stream
#

Ah, whole numbers, makes sense

glass lichen
#

yeah

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obviously you can write the binomial series for sqrt(x) and represent sqrt(x) as a poly

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but sqrt(x) itself is not a monomial

warped phoenix
#

are you supposed to learn long division with polynomials before you learn synthetic division?

glass lichen
#

technically yes, synthetic is the shortcut

warped phoenix
#

welp my book did it the other way around 🥴

serene hearth
#

Can someone explain how they found the value of X and T

#

I'm particularly interested to know how they ended up on the hyperbolic functions

vague coral
#

The characteristic equation is, for the first one,
r^2 + n^2 = 0
r^2 = -n^2 = (in)^2
r = in or r= -in, with i^2 = -1
With those conditions, they applied a formula which is the solution of the differential equation when solutions of characteristic equation are complex numbers

serene hearth
#

I see

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but isn't that normal sin and cos

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Im assuming u mean this formula

vague coral
#

yes but you can do some works to get cosh and sinh

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since cosh =( e^x + e^-x)/2

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wait no

serene hearth
#

no I do not xD

vague coral
#

Its cosh(ix) = cosx

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They used that to get the solutions with cosh and sinh

serene hearth
#

ohh I see

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But isn't that an additional burden

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why not let it stay as cos and sin

vague coral
#

It depends of the exercise, it can simplify calculation

serene hearth
#

hmm

vague coral
#

You only have cosh and sinh, instead of exp and cos and sin

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its much better for calculation

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I saw physics exercise where we needed to use cosh and sinh

serene hearth
#

I see, that clears it!

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Thanks :)

vague coral
#

np

digital rapids
#

i just started using matlab, and i came accross this

#

[J, grad] = lrCostFunction(theta_t, X_t, y_t, lambda_t);

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im not sure what this notation means

wary stream
#

Which part?

digital rapids
#

theta_t = [-2; -1; 1; 2];
X_t = [ones(5,1) reshape(1:15,5,3)/10];
y_t = ([1;0;1;0;1] >= 0.5);
lambda_t = 3;
[J, grad] = lrCostFunction(theta_t, X_t, y_t, lambda_t)

#

Oh

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is it that the function on the rhs produces two outputs

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and J is the first and grad is the second?

wary stream
#

Yes, exactly

digital rapids
#

mb i thought [J, grad] was a matrix but i wasnt thinking straight

heady tusk
wary stream
heady tusk
#

pretend that is a parallelogram, would those to corners be the same

#

those two angles

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yes? no?

digital rapids
#

yeah cos the sides are parallel right

heady tusk
#

yes

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of of course yes

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I'm stupid lol

alpine sable
#

Can someone please explain how

#

What formulas are u used here?

glass lichen
alpine sable
#

Umm what?

glass lichen
#

Gonna need a better question than "what?"

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they did algebra... then did triple angle

alpine sable
#

I understand they used triple angle formula with sin

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But i don't understand how they used it with cos

warped thunder
#

Can anyone teach me how to divide nos with cancelling them out

alpine sable
#

Cos3x = 4cos³x -3 cosx
But here we have 4cos²x-3cosx

#

How do they do it?

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@glass lichen

glass lichen
#

typo

alpine sable
#

Where

glass lichen
#

the line prior....

#

the 2 should be a 3

#

simple.

alpine sable
#

Ah

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How they do it in the first line??

glass lichen
#

what?

#

"it" is so specific

alpine sable
#

How did they get
Cos(3-4 cos² t)

glass lichen
#

simplifiying with algebra

alpine sable
#

I don't understand i am sorry

glass lichen
#

have you done algebra before?

alpine sable
#

What formula did they use?

glass lichen
#

NONE

#

they did algebra

#

not everything is a formula

alpine sable
#

Can u give me an example of what they used?

glass lichen
#

.....

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$3x+1-2x+7=x+8$

ocean sealBOT
alpine sable
#

Oh

#

I understand now

#

Than you so much

#

Is it free?

balmy thistle
#

wah i was typing :C

alpine sable
#

@balmy thistle yeah, I saw that, go ahead.

balmy thistle
#

hi ive got a few questions for an upcoming oral exam.

  1. whats the argument of sine and cosine?
  2. are there implicite functions you cant transform into explicite functions without information being lost? name examples.
  3. why is it useful to translate implicite into explicite forms?

thank you in advance 🙂

rigid smelt
#

hmm is it supposed to be the answer for that exam?

balmy thistle
#

no for self test

glass lichen
#

are these the questions on the exam or designated practice questions?

balmy thistle
#

practice questions, i dont have the exam questions they are in 3 weeks from today

#

and i wont ask them here lol

glass lichen
#

Ok, so post your explanations/answers and someone can read it and comment on it

wary stream
#

What's the exact question?

#

More context is needed than a chart of values

balmy thistle
wary stream
balmy thistle
wary stream
balmy thistle
#

i googled already and found no answer thats why i came here in search of help 😦

wary stream
balmy thistle
#

im from russia sorry for my english

chrome monolith
#

Is the derivative

#

4x - cos 5x^2/2 ?

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Some1 please answer quick

wary stream
chrome monolith
#

I have an exam in a hour

chrome monolith
wary stream
chrome monolith
#

Whg

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Why

wary stream
#

Because it's sin(5x)

chrome monolith
#

Isnt the integral of sin ( - cos x)

frosty drift
#

hey what's up, can you help me solve this?
9x - 7i > 3 (3x - 7u)

chrome monolith
#

4x - cos 5x

wary stream
chrome monolith
wary stream
chrome monolith
#

Do u know the ans

wary stream
#

No

#

I mean u sub for sin(5x)

chrome monolith
#

The ans key has 4x - cos 5x/5

#

Idk how

chrome monolith
wary stream
#

Like I said u sub

#

U sub is kinda like inverse chain rule

chrome monolith
#

Uh

#

Mann idk what to do

wary stream
#

Google it

chrome monolith
#

,w integral (4 + sin 5x)

ocean sealBOT
wary stream
#

That's what you said the answer key said

chrome monolith
#

Yh

#

Idk how they got it tho

#

Lolol

wary stream
#

Use u sub for the trig part

chrome monolith
#

Idk how to

wary stream
#

Google it. You can learn the concept in like 10 minutes rather than have someone explain it for an hour

glass lichen
#

$u=5x\implies \dd{u}=5\dd{x}$

ocean sealBOT
chrome monolith
#

?

wary stream
#

Mosh just showed you u sub

chrome monolith
#

Yeah

#

Doesnt help

glass lichen
#

have you done integrals of trig before...?

chrome monolith
#

Yh

glass lichen
#

so you can integrate sin(x)?

wary stream
# chrome monolith Doesnt help

Literally, if you don't understand the concept, and this pointless back and forth of you not understanding and people trying to explain, because you apparently have less than an hour, as you stated, Google u sub and watch videos on it

chrome monolith
glass lichen
#

+c but yeah

chrome monolith
#

Yeah

glass lichen
#

and yeah, google u-sub if you werent taught it..

#

or just ask what differentiates to sin(5x)

chrome monolith
#

I dnt have time to learn a new concept now

glass lichen
#

well I doubt it's new given you're being asked about it...

#

so it must've been taught.

chrome monolith
#

My teacher never taught it

#

😂

glass lichen
#

I doubt that, but anyway

chrome monolith
#

Bruh

glass lichen
#

just google u-sub or reverse chain rule

chrome monolith
glass lichen
#

with what?
I was just seeing if you at least knew how to integrate trig.

chrome monolith
#

Bro

glass lichen
#

You've already been told it's u-sub

chrome monolith
#

I need help solving the problem

glass lichen
#

and I helped you

chrome monolith
#

With what

glass lichen
#

I did the u-sub part for you...

chrome monolith
#

Asking me how to integrate sin

glass lichen
#

$u=5x\implies \dd{u}=5\dd{x}$

ocean sealBOT
glass lichen
#

That's u-sub

chrome monolith
#

How do i apply it to the question

glass lichen
#

do the sub...

wary stream
# chrome monolith Bro

This is exactly what I mean by the pointless back and forth conversation of a concept you don't understand

chrome monolith
#

I just want to know why its over 5

glass lichen
#

$\int \sin(5x)\dd{x}=\int\frac{1}{5}\sin(u)\dd{u}$

ocean sealBOT
chrome monolith
#

So

#
  • cos 5x / 5
glass lichen
#

+c, yes

primal dew
#

what is the 0 root of 1/0

#

assuming 1/0 is defined

dawn wraith
#

You’re basically asking what’s
1/0^(1/0)

abstract breach
#

,help

ocean sealBOT
#

A brief description and guide on how to use me was sent to your DMs!
Please use ,list to see a list of all my commands, and ,help cmd to get detailed help on a command!

primal dew
dawn wraith
#

Hmm

#

Defined as what though

primal dew
dawn wraith
#

So z to the zth power

primal dew
#

yes

dawn wraith
#

That should be it?

primal dew
glass lichen
#

no fucking clue

#

you're the one defining z

primal dew
primal dew
#

z is a zeroth

glass lichen
#

Im aware z:=1/0

dawn wraith
#

What does it mean when you raise something to the zth?

glass lichen
#

but by your construction it's just z^z

dawn wraith
#

You defined zed to be the number 1/0

primal dew
#

yes

dawn wraith
#

I do not know how to calculate a number in which is raised to that power

#

Only you can, for the reason that you defined the number itself

primal dew
#

ok what happens when you have a 0th root

glass lichen
#

no clue, 0th root doesnt exist in standard math

dawn wraith
#

Impossible, it’s like raising it to the power of something that is divided by 0

glass lichen
#

since 1/0 is an undefined object, you are giving it a definiton and thus need to define 0th root

dawn wraith
#

Smart words that he said^

glass lichen
#

However also in your construction you have that 1=0

spark shadow
#

Is someone free here

primal dew
#

this is all i have

spark shadow
#

I need help

dawn wraith
#

That’s also true, it’s a contradiction.

dawn wraith
glass lichen
#

$\frac{z}{z}=1, \forall z\neq 0$

ocean sealBOT
glass lichen
#

z/z = 0 on your ss, however z/z = 1 since z isnt 0

dawn wraith
#

Anything that you divide by itself will result in the number 1

glass lichen
primal dew
#

but z/z = 1/0 * 1/0

#

and i did the math

dawn wraith
primal dew
#

and got 0

dawn wraith
#

Which means you’ve got a contradiction

primal dew
glass lichen
#

holy

dawn wraith
#

You define that

#

It’s your number

glass lichen
#

z is your number

#

I dont give a fuck about z

#

Your system that includes z looks to be equipped with operations from the real numbers, thus z/z=1

primal dew
#

but

glass lichen
#

yeah, so you showed 1=0 in your system

#

since you are using facts about rational/real numbers

#

either z acts as 0 or as z

dawn wraith
primal dew
#

what?

dawn wraith
#

You’re saying 0/0 * 1/0 is 0/0 * z

#

But 0/0 is undefined

primal dew
#

0/0 is 0 zeroths

#

so 0/0 = 0

glass lichen
#

wheel algebra moment sully

dawn wraith
#

Okay, but you have a contradiction

#

So you’ll have to do something about it

primal dew
#

what could i do?

glass lichen
#

It's your system

dawn wraith
#

Redefine 0/0

#

You do what you want

glass lichen
#

This is like JK Rowling asking a random person to write the next Harry Potter

primal dew
#

i mean i could say 0/0 = 1 but thats sounds very wrong

glass lichen
#

oh and z=1/0 means perfect sense...

dawn wraith
#

Go ahead and define it, it’ll hopefully fix the contradiction

primal dew
#

if 0/0 = 1 then z/1 = 1 and sqr z/z = 1

#

but ill do that

dawn wraith
#

Good!

primal dew
#

wait

#

no

#

z -z would = 1

glass lichen
#

Yeah, this is why 1/0 stays undefined

dawn wraith
#

XD

glass lichen
#

cause assuming it is defined causes things to break

primal dew
#

or i could just say that z is not non-zero

glass lichen
#

so z=0

dawn wraith
#

And then you get 1=0

#

Since z = 1/0

primal dew
#

no if z is not-non zero it just means non-zero is a set of numbers

dawn wraith
#

Ugh

glass lichen
#

Im gonna say this bluntly: you are trying to define a system, it makes no sense to be asking other people on how the system works.

primal dew
#

well im trying to see if the system works

glass lichen
#

it doesnt

#

cause you have simply taken the real numbers and added a new element in without redefining the operations.

#
  • and * you're using act on R, not R w/ {z}
primal dew
#

wait the 0th root of 1 is 1

dawn wraith
#

?

#

so 1^z is 1, okay

primal dew
#

i guess

spring sierra
#

how would you approach this question

alpine sable
#

a) sine rule

spring sierra
#

because I've tried the sin rule

#

angle A is 51.1

#

but if that's 51.1

#

it means the angle on th eother side is obtuse

#

and since it's isosceles

#

that would make two angles obtuse?

#

in a triangle

alpine sable
#

wdym the other angle

#

what angle

spring sierra
#

those two

dawn wraith
#

pay attention

#

there are 2 possibilities

spring sierra
#

oh

#

do i take away

#

from 180

dawn wraith
#

due to the identity
sin(180 - x) = sin(x) existing

spring sierra
#

OH YEAH

#

thank you

dawn wraith
#

piece of cake

short sand
#

Okay, practical question.
I have a set of products that sell at a known velocity.
I represent this velocity as a decimal of capacity in slots.
For example, Product A sells 0.1 slots per day. After 10 days it will sell through 1 slot.
A store has a set positive integer number of slots. 23, for example.
I can set the quantity of products in a store as a positive integer number of slots.
I want to set the slot quantity for each product in such a way as the minimum days of any individual product is as high as possible.
Sample set: A: 0.1 slots/day, B: 0.25 slots/day, C: 0.1 slots/day. D: 0.55 slots/day, E: 0.75 slots/day
Slot Capacity: 27

civic elbow
#

Confused on how to do these 2 problems

minor heath
civic elbow
#

Wait would the second one be h?

warped flower
#

ASA or SSS rules

minor heath
#

just a hint that all those right triangles, the two triangles and the entire triangle itself, are similar to each other

civic elbow
#

Still a little confused

#

If you can, could you maybe explain how to do one of these problems?

minor heath
civic elbow
#

Ya EHG

#

EHF*

#

And GED

minor heath
#

and then the last one?

civic elbow
#

FDJ

minor heath
#

wrong side order, since you did each in (shorter side, longer side, hypotenuse)

#

just apply that to the triangle you named

civic elbow
#

Ah

#

So I am a little confused what to do next

minor heath
civic elbow
#

We can use FJD and GED

minor heath
civic elbow
#

Ah ya

minor heath
#

now, use this property of similar triangles: (chosen side of 1st triangle/same side of 2nd triangle) = (another chosen side of 1st triangle/same other side of 2nd triangle)

#

for example, you can set d/j = e/f

civic elbow
minor heath
#

then apply that to the next question

civic elbow
#

Second one then is h?

minor heath
#

ok

#

yea i think thats it

civic elbow
#

Is it ok if I show 2 more

minor heath
#

sure

civic elbow
#

I think I know the answers

#

Just want someone to check

minor heath
#

kk

civic elbow
#

Think j and h?

glass lichen
#

yes

minor heath
#

yea

lone dagger
#

Could someone explain me this step?
I know it should give -0,4, but that's not the issue. How do you even get the 0,4?

thorn kindle
#

,calc 1/2.5

ocean sealBOT
#

Result:

0.4
lone dagger
#

Oh

#

xD

thorn kindle
#

But it should be -0.4

lone dagger
#

Gotta get my brain ready for the test tomorrow.

#

Thanks haha

thorn kindle
#

,calc (1/10)^(-1/2.5)

ocean sealBOT
#

Result:

2.5118864315096
thorn kindle
#

@lone dagger not 0.4

#

-0.4

lone dagger
#

Yep I know that is wrong xd

thorn kindle
#

Alr

#

Gl

lone dagger
#

Thank you

tiny agate
#

hey guys, i have a differential geometry question but i figured it could be a little advanced so i asked in topology-and-geometry, it's an exercise my professor solved that i didn't get, can anybody take a look?
thank you!

loud iris
#

find general solutions of sinx + cosx = 2^1/2

#

can someone help me out ?

rigid smelt
#

If you divide sqrt(2) on both sides

#

You will notcie a very particular patterns

#

sin(pi/4)=cos(pi/4)=1/sqrt(2)

loud iris
#

hold up wait

#

maybe 2 mins

rigid smelt
#

Now substitute this into
sin(x)/sqrt(2)+cos(x)/sqrt(2)=1

loud iris
#

lemme absorb what u said

rigid smelt
#

Sure

#

We are making use of the addition identity here

loud iris
rigid smelt
#

Ok dont focus on that too much

rigid smelt
loud iris
rigid smelt
#

Alright

#

So you also know that sin(pi/4)=1/sqrt(2) right?

loud iris
#

yea

#

that makes it sinxsinpi/4 + cosxcosi/4

#

ok

rigid smelt
#

So we can rewrite the equation as sin(x)sin(pi/4) + cos(x)tsqrt(2)=1

loud iris
#

i think i got it

rigid smelt
loud iris
#

we can then move on to convert this to cos(x-pi/4)

#

yeap

#

thanks

rigid smelt
#

Basically this is a method of solving equations in the form asin(x)+bcos(x)=c

loud iris
#

im good to go

loud iris
#

mind go poof at times disables me to think about simple algebra at times

rigid smelt
#

Well if you are interested, the first to doing that is dividing both sides by sqrt(a^2+b^2)

#

And the steps later on are just what we did

rigid smelt
#

Yes kind of

loud iris
#

a=rcosy and b=rsiny

#

like that

#

where

rigid smelt
#

The idea is that we want to convert it into sin(x +/- y) or cos(x +/- y)

loud iris
#

r=(a^2 + b^2)^1/2

loud iris
#

@rigid smelt bruh

#

im getting wrong ans 😭

warped phoenix
#

for y = kf(x), the function is stretched away from the x axis if k > 0, compressed towards the x-axis if 0 < k < 1, and reflected across the x-axis if k > 0, right?

#

just to make sure im saying that right

warped phoenix
#

<@&286206848099549185>

#

?

#

anyone?

queen wigeon
#

if 0<k<1, the function is compressed, if k > 1, the function is stretched away from the x-axis, and it is reflected over the x axis if k < 0

warped phoenix
#

ah ok

ocean sealBOT
#

TheMane3

warped phoenix
#

why do you shift the graph to the right two units when inside the parenthesis the 2 is negative? @queen wigeon

#

shouldn't it be moved two units to the left since f(x + k) is shifted to the right whereas f(x - k) is shifted to the left?

inner adder
#

hello

#

i have some question it is not in math but i hope someone can help me :/

#

its on german hope someone you unserstand with translator or somethink

warped phoenix
#

ok disregard my last question then

#

how do they know that g(x) = f(x + 2) + 7 ?

#

it doesn't say that anywhere in the question

inner adder
#

its on german

#

Subject: Technology

glass lichen
#

so (x+2)^2 is clearly f(x+2)

warped phoenix
#

$(x +2)^2 = (1x+2) (1x+2)$

ocean sealBOT
#

TheMane3

warped phoenix
#

$(1x+2) (1x+2) = x^2 + 4x + 4$

ocean sealBOT
#

TheMane3

warped phoenix
ocean sealBOT
#

TheMane3

glass lichen
#

No....

#

f(x)=x^2

warped phoenix
#

but in (x + 2)^2 the degree isnt being directly distributed to x

glass lichen
#

ik

#

so?

warped phoenix
#

so how can it be x^2

glass lichen
#

x+2 is being squared

#

correct?

warped phoenix
#

right

glass lichen
#

so if f(x)=x^2, f(x+2)=(x+2)^2

#

cause all f does is square whatever you put into it

warped phoenix
#

ahh

nimble meteor
#

I'm so confused why do we have to use double angle identities?

#

like can't we just find the cos of an angle and then just multiply it times two?

oak chasm
#

Because if you get a cosine of 1, double that is 2, right?

nimble meteor
#

yeah

oak chasm
#

But you can't get a cosine of double the angle that's 2, right?

#

Because cosine only goes up to 1.

nimble meteor
#

oh yeah

#

oHHHHHHHHHHHHHHH

#

dang that actually makes sense

#

THANKSSSSSSSSSSSSSSSSSSSSSSSSS

oak chasm
#

No problem.

nimble meteor
#

dang your smart lol

alpine sable
#

I want to say that I computated something incorrectly but cannot see any mistakes

#

Not sure where the difference between -17 and -34 (my answer) comes from

#

ait

#

wait

#

I think my error is I set it = 0 not = 17 or something along these lines

#

Would love if someone can confirm this for me

lilac raptor
#

If you have two numbers and you add those two numbers than the numbers that you added have numbered the second number that has just been added due to the subtraction of the first number that was numbered by the first number.

#

true?

glass lichen
#

what

wind swallow
#

what

sour pasture
#

@alpine sable that’s right, your error is what you set it equal to.
the RHS should be (w - w_0)

#

@lilac raptor
are you are saying if a + b = c,
Then b = c - a?

alpine sable
#

whats the best textbook for practice questions for calc I and II?

vestal hollow
alpine sable
#

didnt even see that channel, thanks!

vestal hollow
#

How do you do this? I've looked at some examples and I don't get it pensivebread

#

How do you even do the base case? Do you sub in n, k = 1? Bc I saw some using n = 1 and k = 0, 1

muted raft
#

you are inducting on n

#

not on k

#

or rather proving k follows from inducting n

vestal hollow
#

Is this oaky so far?

#

How am I supposed to show that it's an integer?? The sum of two integers is an integer but that requires showing that n choose k and n choose (k-1) are also integers, which is what I'm trying to do thonk

gusty ravine
#

your statement is P(n): n choose k is an integer for k where 0<= k <= n

glass lichen
#

You use a strong hypothesis keep in mind

gusty ravine
#

prove P(1) to be true. Assume P(i) is true and deduce P(i+1) gg fishthonk

glass lichen
#

you did the n=1 case, then assume it holds for n=j, then show n=j+1 is true

alpine sable
#

hey

glass lichen
#

$\binom{j+1}{k}=\binom{j}{k-1}+\binom{j}{k}$

alpine sable
#

i got a calc question

ocean sealBOT
glass lichen
#

clearly

alpine sable
#

can i ask here

#

ok

glass lichen
#

the 2 co-efficients on the RHS are integers by the hypothesis, and sum of integers is an integer

vestal hollow
#

Wait I'm an idiot LOL by "by the hypothesis" you mean the part where I say "assume it holds for n = j" right?

glass lichen
#

You need a strong hypothesis, so $\binom{j}{k}\in\mathbb{Z}, 0\leq k\leq j$

ocean sealBOT
vestal hollow
glass lichen
#

yes

vestal hollow
#

Just making sure bc it looks the same

#

Sweet

#

Then I think I'm done

glass lichen
#

yeah it's just 2 lines

vestal hollow
#

Maybe I shuld include a closing statement

#

But everything else is okay?

glass lichen
#

yeah

vestal hollow
#

Sweet, thanks Mosh

hardy vault
obsidian marsh
#

sl e

#

someone who knows Mathematica can tell where my plot is?

#

lol

oak chasm
#

@obsidian marsh What's the domain of e^t?

#

,w Table[N[5(1 - e^(-5000t))], {t, 0, 25000, 2500}]

ocean sealBOT
oak chasm
#

Looks like you should be looking around y = 5 or so.

#

,w Plot[5(1 - E^(-5000x)), {x, 0, 25000}]

ocean sealBOT
oak chasm
#

@obsidian marsh ^

rocky axle
#

had this come up in a test the other day and everyone failed to get it right
I'm wondering how to go about solving this

sleek elbow
#

bro what is that im definitely not qualified in the slightest to do that

clever locust
#

Well notice that

$$\int_{-\infty}^\infty \frac{\dd{x}}{1+4\pi^2(x-5000)^2} = \int_{-\infty}^\infty \frac{\dd{x}}{1+[2\pi(x-5000)]^2}$$

Then do the substitution $u=2\pi(x-5000)$, $\dd{u}=2\pi \dd{x}$, so you have

$$\frac{1}{2\pi} \int_{-\infty}^\infty \frac{\dd{u}}{1+u^2}$$

From there you should probably be able to do it yourself

ocean sealBOT
#

Lorago

timid wind
#

ok?

rocky axle
clever locust
#

Np

strong crater
#

why does the answer take the reciprocal of tan?

#

the description even says that since (3pi/2 + theta) is in the 4th quadrant so shouldn't it be -tan?

oak chasm
#

@strong crater Because tangent is the slope of an angle. When you add 3/2 pi to an angle, it's perpendicular to the original angle. What happens to the slope when you find the perpendicular slope?

#

If the original slope is m, what's the perpendicular slope?

strong crater
#

-1/m

oak chasm
#

Right, so if the original slope is tan(theta), the perpendicular slope is -1/tan(theta).

strong crater
#

ohhhh i see

#

okie thanks

oak chasm
#

No problem.

bold shard
#

i have a question about using the standard normal probabilities table. I have to look up the probability that : P(-1.72 < Z < 1.22) , and im not sure how to go about doing this. I thought that you subtract (1.22 - [-1.72]) and then look up the answer in the table but that was wrong.. any help?

bold shard
#

<@&286206848099549185>

slate monolith
#

they can prob be of more help

bold shard
#

ight

rocky dock
#

the 1st screenshot is my solution to the question above

#

any ideas why im wrong?

slate monolith
#

16 should be fine

#

cause its 4 + 4

#

no negative numbers

#

so

#

[0, infinity)

#

sqrtx can never be -4

#

unless imaginary

rocky dock
#

hmm i dont quite understand

#

why was my interval notation incorrect?

slate monolith
#

so u said sqrtx + 4 =/ 0

#

that will always be true

#

since the sqrt of a pos number

#

is always positive

#

the only issue comes when x < 0

#

which you mentioned

rocky dock
#

oh, so if it's a problem like this

#

the domain will always be [0,∞)?

slate monolith
#

the denominator will never be 0

#

and it will only not exist when x < 0

#

so yes

rocky dock
#

ok, so the +4 ensures it'll never be 0

slate monolith
#

yes

rocky dock
#

so if the x was a normal x and not the sqrt

#

it would have to be > 0 only right?

slate monolith
#

well

#

both of them?

#

so x - 2 / x + 4?

#

or just 1

rocky dock
#

both and just 1 if you dont mind explaining the diff

slate monolith
#

okay so

#

if both

#

then its for all x but x = -4

#

cause thenu have -6/0

#

vertical asymptote

#

if sqrt on top but not bottom

#

[0, infinity)

#

if just on top

#

same thing as well

rocky dock
#

ok

#

appreciate the help!

#

you rock!

slate monolith
#

sure thing 🤘

boreal sinew
#

Does theorem corresponding to the last line have a name?
$$
\begin{equation}
\begin{cases}
f: X \to Y; \
g: Y \to Z; \
f^{\rightarrow}(S_x) = { y \in Y : \exists x \in S_x. y=f(x) } \
g^{\leftarrow} = { z \in Z: \exists y \in Y. z=g(y) } \
[g \circ f]^{\rightarrow}(S_x) = { z \in Z: \exists y \in f^{\rightarrow}(S_x) \cap g^{\leftarrow}. z=g(y) } \
[g \circ f]^{\rightarrow}(S_x) = [g_{\vert f^{\rightarrow}(S_x) \cap g^{\leftarrow}} \circ f^{\vert f^{\rightarrow}(S_x) \cap g^{\leftarrow}}]
\end{cases}
\end{equation}
$$
Note: $g_{\vert S_y}$ is domain restriction of $g$ to $S_y$ while $f^{\vert S_x}$ is corestriction of $f$ to $S_y$. I.e.
$$
\begin{equation}
\begin{cases}
f^{\vert S_y}: X \to S_y \
g_{\vert S_y}: S_y \to Z
\end{cases}
\end{equation}
$$

ocean sealBOT
#

JohnDark
Compile Error! Click the errors reaction for more information.
(You may edit your message to recompile.)

boreal sinew
#

Note: $g_{\vert S_y}$ is domain restriction of $g$ to $S_y$ while $f^{\vert S_y}$ is corestriction of $f$ to $S_y$. I.e.
$$
\begin{equation}
\begin{cases}
f^{\vert S_y}: X \to S_y \
g_{\vert S_y}: S_y \to Z
\end{cases}
\end{equation}
$$

ocean sealBOT
#

JohnDark
Compile Error! Click the errors reaction for more information.
(You may edit your message to recompile.)

wicked axle
#

can I get some help on this?

slate monolith
wicked axle
#

:o

#

help help! :D

slate monolith
#

lemme see

wicked axle
#

so what ive done so far is find the coordinates of B

#

we also know the x and y intercepts of the line

#

im confused where to go from here

#

or if im even on the right track

slate monolith
#

u gotta find the slope between A and B

#

the x intercept is C

#

u gotta find C as a function of r

#

show me what u got

wicked axle
#

one sec let me try and do it on paper this time

boreal sinew
# wicked axle can I get some help on this?

Please, don't break rules next time.

  1. Before asking a question, make sure that the channel you are using is not currently in use. An occupied channel would generally have an ongoing discussion or a trailing unanswered question. Likewise, when you are done using a channel, make this clear so that it's open for others to use.
slate monolith
#

so like 🤷‍♂️

boreal sinew
#

Indeed, my bad

jagged imp
#

there are other open channels, and 20 minutes isn't that long

#

plus they'd already posted in precalc

slate monolith
#

true

#

hmm

wicked axle
#

and like the other guy said no one had typed for a while

slate monolith
#

lets just move on

#

pahul did u get any work on paper

wicked axle
#

yeah gimmie sec still doing some work

boreal sinew
#

@slate monolith Where would you suggest me post the question that I posted here earlier? It is about function composition, domain restrictions and corestrictions. The topic of function composition is at basic level is covered in Intermediate algebra course here (https://www.mesacc.edu/~scotz47781/mat120/), but I'm unsure to which branch of mathematics it actually belongs because functions and their compositions are ubiquitous.

slate monolith
boreal sinew
#

I'll copy the question from here to there, thank you! @slate monolith

wicked axle
#

so should I be trying to find the equation of the line first?

slate monolith
#

find the slope between A and B

#

intrecept is A

wicked axle
#

$m=\frac{r-sqrt\left(r^2-\frac{r^4}{4}\right)}{-\frac{r^2}{2}}?$

ocean sealBOT
#

Pahul's Uncle

wicked axle
#

that what im getting for slope lol

#

not simplified but yeah i think im doing it wrong

queen wigeon
wicked axle
#

oh :o

#

so maybe it's right

#

@slate monolith can you confirm?

slate monolith
#

um

#

ur syntax is confusing me

#

usually do the greater x first

#

so (x-1)^2 + y^2 - 1 = x^2 + y^2 - r^2

#

-2x = - r^2

#

x = r^2/2

#

so

#

this gets messy

queen wigeon
#

wait, doesnt x = $r^2/2$

slate monolith
#

r^2/2 + y^2 = r^2

ocean sealBOT
#

mchen10

slate monolith
#

mb mb+

wicked axle
#

yeah

#

i got x = r^2/2

slate monolith
#

yeah yeah

#

so r^4/4 + y^2 - r^2 = 0

wicked axle
#

yeah got that

slate monolith
#

looks good

slate monolith
wicked axle
#

and we know the y intercept is r

slate monolith
#

ye

#

so y = mx + r

crystal tapir
#

pls help @here

slender forge
# crystal tapir pls help @here

An easy way to do this is to pick a point (or probably several) on the given graph look at its slope then plug in that point(s) into each of the choices and see if it matches

crystal tapir
#

oki lemme try thx

slate monolith
#

see if as u change x or y its constant or changing

#

or inc/decreasing

summer goblet
crystal tapir
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how do i do this @here

fringe yoke
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Is this an exam? It sais 1 mark

slate monolith
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dont ping here or anything

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dont ping anyone unless u waited 15 min for helper

crystal tapir
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2020

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tech free

slate monolith
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ah

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is this calc @crystal tapir

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so from what i understand

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g'(x) = 2x

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so g = x^2

jagged imp
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@here is disabled by the way, just post your question and if it doesnt get answered for 15 mins you can ping helpers

slate monolith
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mhm

jagged imp
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in case you need help on any other questions in future

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oh this doesnt give working though since its one mark

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nvm

crystal tapir
alpine sable
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can somebody explain question 3

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i know the answer

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but idk how exactly it works

slate monolith
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3 busses or walk

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then 3 buisses

alpine sable
slate monolith
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read above

alpine sable
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oh hmmm

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i get it i think

rugged bronze
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Find all values of $x$ such that
$$\frac{x^2 + x + 3}{2x^2 + x - 6} \ge 0.$$
Note: Your solution should be thorough, and explain why all your values are the only values that satisfy the inequality.

ocean sealBOT
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MathMemer

rugged bronze
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writing problem for aops

slate monolith
indigo jetty
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@rugged bronze what have you done so far?

gritty gull
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"A group of 4 students went to drink pearl tea and study at a local tea shop. The shop offers 12 different flavors of pearl tea. What is the probability that at least 2 students ordered the same flavor? Express your answer as a decimal, and round to the nearest ten thousandths."

May anyone explain this question please? It's on my Algebra 2 quiz and I'm really stressing out about it

woven pollen
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One minus they all pick a different tea. 1 - [(1/12) * (1/11) * (1/10) * (1/9)]

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S = {all different, at least two}. So 1 - P(all different) = P(atleast two)

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note: 'at least 2' contains many more combinations, but in this case we do not have to worry about enumerating them.

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e.g. 'exactly 3' is in 'at least 2'.

fierce summit
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what i dont think it would be that high

woven pollen
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yay, it will be high. because it includes at least 3 + at least 4 + exactly 3 + exactly 4.

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meaning, at least 2 also includes they all order the same tea, etc

fierce summit
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probably not about 99.99% as answer tho

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maybe its actually 1 - [(12/12) * (11/12) * (10/12) * (9/12)]

woven pollen
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OH! YES. Ooops.

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😊

fierce summit
tired locust
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I wanted to prove that the top compound proposition is a tautology by using logical equivalences. Does my work look correct here? (CDE = conditional-disjunction equivalence here)

woven pollen
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Yes.

tired locust
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Woot! I worked on this for longer than I care to admit.

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Thanks for taking a look

woven pollen
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yay. those things take forever.

tired locust
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Every time I made a tiny error and had to scrap and start from scratch

woven pollen
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I remember have to prove +0 = -0. it was like 4 lines and it took me about 4 hours to build.

tired locust
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I'm always amazed at how much working on problems helps solidify. Every time I think about being lazy and skipping the exercises, I remember how valuable they are

tired locust
gritty gull
dim falcon
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seriously the last rule of this server is kinda pointless

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i mean, it kinda makes you think... my major my choices lmao

wide fern
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hey guys ive been working on this question for robotics for the past few hours

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from what i remember, i need to use the lagrangian, except im not fully sure how to do it

slate monolith
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aye physics

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ur better asking this in the physics discord but

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Kinetic energy is 1/2 mv^2

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is that a spring

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so ma = F - kx

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a = dv/dt

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do u have an idea of what im doing

visual kernel
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what are the solution for task 1 and 2